sim: common: split up acinclude.m4 into individual m4 files

This file is quite large and is getting unmanageable.  Split it apart
to follow aclocal best practices by putting one-macro-per-file.  There
shouldn't be any real functional changes here as can be seen in the
configure script regens.

sim/erc32/configure

@@ -631,6 +631,16 @@ ac_includes_default="\
 
 ac_subst_vars='LTLIBOBJS
 LIBOBJS
+sim_reserved_bits
+sim_hw
+sim_hw_objs
+sim_hw_cflags
+sim_default_model
+sim_scache
+sim_float
+sim_endian
+sim_bitsize
+sim_alignment
 cgen_breaks
 READLINE
 TERMCAP
@@ -749,17 +759,7 @@ PATH_SEPARATOR
 SHELL
 WERROR_CFLAGS
 WARN_CFLAGS
-sim_reserved_bits
-sim_inline
-sim_hw
-sim_hw_objs
-sim_hw_cflags
-sim_default_model
-sim_scache
-sim_float
-sim_endian
-sim_bitsize
-sim_alignment'
+sim_inline'
 ac_subst_files=''
 ac_user_opts='
 enable_option_checking
@@ -11785,7 +11785,6 @@ _ACEOF
 
 
 
-
 # Check whether --enable-werror was given.
 if test "${enable_werror+set}" = set; then :
   enableval=$enable_werror; case "${enableval}" in
@@ -12037,6 +12036,18 @@ ac_config_commands="$ac_config_commands Makefile"
 
 ac_config_commands="$ac_config_commands stamp-h"
 
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 cat >confcache <<\_ACEOF
 # This file is a shell script that caches the results of configure
 # tests run on this system so they can be shared between configure